In general, gas in an oral cavity means gas which is generated from an oral cavity of humans. Oral malodor, a kind of halitosis consists mostly of volatile sulfur compounds like hydrogen sulfide and methyl mercaptan generated from the oral cavity due to the anaerobic breakdown of proteins into individual amino acids which is caused by tongue coating or periodontal diseases.
Meanwhile, exhaled breath which is generated while humans breathe is discharged through an oral cavity and a nasal cavity to the outside, and contains gas constituents relating to human metabolism and respiration. In particular, a patient having an internal disease expels a bad smell containing volatile organic compounds such as acetone and alcohol, ammonia and the like according to the type of disease and inflammation. It is well known in the related art that constituents of gas, which is generated from an oral cavity or discharged through an oral cavity or a nasal cavity while breathing, relate to the nature of diseases. For example, a physiological phenomenon of when a tongue is coated at a lower side thereof generates hydrogen sulfide, a pathological phenomenon of when periodontal disease occurs generates methyl mercaptan, aceton relates to diabetes, and ammonia relates to a kidney disease. Furthermore, measurement of the concentration of carbon monoxide of exhaled breath of humans is considered a method of objectively evaluating a smoking condition. Accordingly, if predetermined constituents of gas in an oral cavity or exhaled breath are analyzed and their concentrations are measured, it is possible to schematically diagnose an oral cavity disease and an internal disease of humans. The diagnosis method may be useful in diagnosing an internal disease of a patient having oral malodor and a disease of infants or patients in the intensive care unit who are difficult to communicate to doctors. The method can also be used to diagnose the condition of a disease of domestic animals.
It is necessary to use a very precise and high-sensitive measuring apparatus in order to analyze the gas in the oral cavity or the exhaled breath of humans. Currently, in order to separate the gas constituents from each other, a gas chromatography is used. In order to quantitatively analyze the separated gas constituents, it is necessary to use various types of detectors such as a thermal conductive detector, a flame ionization detector, an electron capture detector, a flame photoelectronic detector, and a heat ionization detector, or a mass spectrometry detector.
The above-mentioned analysis apparatuses are costly and operated by professionals having specific knowledge and technique regarding the apparatuses, which causes an increase in the cost of operation. For this reason, the apparatuses are used only by a small minority of research organizations.
In order to avoid the above-mentioned problems of the gas chromatography, a portable and standalone type of oral malodor measuring apparatus is provided to clinicians or hospitals to measure gas in the oral cavity. For example, gas analyzing apparatuses such as Halimeter (Interscan Corporation in the USA) are extensively used.
In respects to a known oral malodor measuring apparatus, an electrochemical gas sensor that senses oral malodor is disclosed in U.S. Pat. No. 4,017,373. In this invention, only the total amount of volatile sulfur compounds of the sensed oral malodor gas is displayed. For this reason, there is a problem in that hydrogen sulfide (H2S) and methyl mercaptan (CH3SH) cannot be discriminated from each other. That is, whether the oral malodor of the patient is based on a physiological factor or a pathological factor cannot be determined; as a result, the patient cannot be precisely diagnosed. Furthermore, the amount of oral malodor gas which is to be measured is 500 ml or more. For this reason, the concentration of oral malodor may be reduced due to the air around the measuring apparatus. As a result, the constituents of oral malodor cannot be precisely analyzed and malfunction of the apparatus may occur due to gas constituents in the air.
In addition, FIG. 1 illustrates another apparatus for monitoring oral malodor gas. In the apparatus, if patient bite a mouthpiece 1 to analyze oral malodor, an oral malodor gas is transferred through a mouth filter 2 in the mouthpiece 1 by pump 4, and then constituents of oral malodor gas is analyzed by using a sensor 5. An electromagnetic valve 3 is opened, and a pump 4 is operated to refresh the sensor 5 by using the air that is filtered by a carbon filter. In the apparatus, a portion of effective volatile sulfur compounds of the oral malodor gas is adsorbed on the mouth filter 2 in the mouthpiece 1 during sampling of the oral malodor gas. Therefore, it is difficult to precisely analyze the oral malodor gas. Furthermore, the sampling amount of oral malodor gas is used 80 ml. For this reason, it is difficult to precisely analyze the volatile sulfur compounds. In addition, the only total amount of volatile sulfur compounds such as hydrogen sulfide or methyl mercaptan is displayed in the apparatus. For this reason, patients having physiological oral malodor and pathological oral malodor cannot be distinguished from each other.
In order to avoid the above-mentioned problems, that is, a difficulty in discriminating between the physiological and pathological oral malodors of the gas in the oral cavity, Korean Patent Application No. 2004-91837 discloses an apparatus for analyzing constituents of oral malodor gas. The apparatus shown in FIG. 2 is provided with a first three way valve 12 that is connected to a control valve 12a at an end thereof, to a mouthpiece tube at another end thereof, and to an end of a sampling loop 11 for storing sampled oral malodor gas at a third end thereof, a second three way valve 16 that is connected to another end of the sampling loop 11 connected to the third end of the first three way valve 12 at an end thereof, to a syringe 14 through a check valve 13 at another end thereof to absorb the oral malodor gas and then store the absorbed oral malodor gas in the sampling loop 11, and to a solenoid valve 15 at a third end thereof, a third three way valve 20 that is connected to a solenoid valve 15 at an end thereof, to an air flow tube 17 through which the filtered air flows at another end thereof, to a tube 19 connected to a semiconductor sensor 18 at a third end thereof, an air filter 22 that is connected to an end of the air flow tube 17 to filter the air, a suction pump 21 that is connected to another end of the semiconductor sensor 18 to pass the air and the diluted oral malodor gas through the semiconductor sensor 18, and a speed controller 23 that is connected to an end of the air filter 22 to control an amount of air so that a ratio of the oral malodor gas provided from the solenoid valve 15 and the air is in the range of 1:1 to 1:2.
If the mixing ratio of the oral malodor gas and the filtered air is very low, the relative humidity is insignificantly reduced. However, if the mixing ratio of the oral malodor gas and the filtered air is very high, the oral malodor gas is excessively diluted to have a significantly reduced concentration. For this reason, it is preferable to control the ratio by using the speed controller 23 so that the ratio is in the range of 1:1 to 1:2.
Additionally, in a known invention, the air filter 22 is used to recover a gas sensor after gas analysis. However, in the invention of the above-mentioned patent, the air filter 22 is used to reduce the relative humidity of sampled oral malodor gas. In particular, in the known invention, the oral malodor gas is analyzed while a patient opens his mouth. Therefore, various types of gases in the air may be mixed with the oral malodor gas. However, in the invention of the above-mentioned patent, a filter that is formed of silica gel and activated carbon is used to filter unknown gas constituents in the air and to mix the filtered air and the oral malodor gas, which enables the oral malodor gas to be precisely analyzed.
If the oral malodor gas is analyzed, the relative humidity in the oral cavity is almost 100% at a body temperature of 36.5° C. Accordingly, if the oral malodor gas is inhaled into an apparatus for analyzing oral malodor at room temperature in the range of 20 to 28° C., water condenses at the surface of the sensor, which erroneously outputs sensor signal. In order to avoid this, in the present invention, the air filter 22 including silica gel is used to filter the air before the air is inhaled into the apparatus, and the filtered air is mixed with the oral malodor gas to reduce the relative humidity at the sensor, thus preventing water from condensing on the surface of the sensor.
The semiconductor sensor 18 is provided with a oral malodor gas measurement unit 18a that includes a gas sensor having predetermined selectivity in respects to hydrogen sulfide, and an oral malodor gas measurement unit 18b that includes a sensor having predetermined selectivity in respects to methyl mercaptan.
However, in the above-mentioned known configuration, the apparatus for analyzing the constituents of the oral malodor gas can only analyze only physiological oral malodor gas and pathological oral malodor gas of a patient, which are two types of oral malodor gases in the oral cavity, but cannot analyze other volatile organic compounds of the gas in the oral cavity and constituents of the exhaled breath.
In addition, it is required that the two types of sensors used to analyze two types of gases have selective reactivity in respects to the gases. Accordingly, the selection of the sensor is limited. The wrong selection of the sensor increases the possibility for error in terms of measured value, thus disturbing a precise analysis.
In order to overcome the above problems, there has been applied KR Patent Application No. 10-2007-83383 by the present applicant as shown in FIG. 3, which is related to a gas analyzing apparatus of the oral cavity gas and the exhaled breath comprising a filter 110 that is filled with an adsorption and dehumidifying substance such as silica gel, calcium chloride, and activated carbon to filter the outside gas by adsorbing polar molecules and non-polar molecules in the outside air and by removing water in the outside air in order to use the outside gas as carrier gas, a first solenoid valve 120 that is connected to the filter 110 at an end thereof so as to provide carrier gas passing through the filter 110 thereinto and controls a flow of the gas in the oral cavity or the exhaled breath flowing through a connection port 121 thereto; a second solenoid valve 130 that is connected through a connection tube 122 to the first solenoid valve 120 at a first port thereof, connected through a bypass tube 131 to a third solenoid valve 140 at a second port thereof so as to bypass the carrier gas, and connected to a sampling loop filled with the gas in the oral cavity or the exhaled breath collected by the third solenoid valve 140 at a third port thereof; a fourth solenoid valve 150 that is connected through the connection tube 122 to the third solenoid valve 140; a fifth solenoid valve 160 that is connected through an upper bypass tube 161 provided with a speed controller to a port of the fourth solenoid valve 150; a column 162 that is connected to another port of the fourth solenoid valve 150 to allow the gas in the oral cavity or the exhaled breath and the carrier gas to sequentially flow therethrough; a sensor chamber 163 that is connected to the column at an end thereof and has a sensor; a lower bypass tube 164 that is connected to another end of the sensor chamber at an end thereof and to the fifth solenoid valve 160 at another end thereof and is provided with another speed controller; a pump 170 that is connected to the fifth solenoid valve 160 to draw the gas in the oral cavity or the exhaled breath and the carrier gas and then discharge the gas in the oral cavity or the exhaled breath and the carrier gas to the outside; a control unit 180 that is connected to the first to the fifth solenoid valves 160, the sensor chamber 163, and the pump 170 to control the first to the fifth solenoid valves 120, 130, 140, 150 and 160, the sensor chamber 163, and the pump 170; and a display device 190 that measures concentrations of the gases by using signal and calculation treatments in the control unit 180 to display results.
In the above structure, the bypass tube 131 that bypasses the carrier gas functions as follows. First, the bypass tube 131 prevents the inside of the sampling loop 132 from being contaminated by residues and impurities probably contained in the carrier gas. Second, when residues by the collected gas remain in the sampling loop 132, the bypass tube 131 prevents the residues from polluting the column 162.
However, the bypass tube 131 can be omitted as long as there is no risk of contamination of the sampling loop 132 by the carrier gas and the collected gas. According to this, the second solenoid valve 130 and the third solenoid valve 140 can be removed.
The above structure is disclosed in KR Patent Application No. 10-2008-0080918 filed on the basis of the priority of KR Patent Application No. 10-2007-83383 and illustrated in FIG. 11 through FIG. 13 of the present invention.